Golf club head

Abstract

To provide a golf club head that is improved in repulsion performance in a principal hitting position by reducing a sweet spot without impairing durability.SOLUTION: A golf club head 1 includes a face part 2. The face part 2 includes: a face 21 that is a surface for hitting a ball; and a face rear face 22 that is a surface on an opposite side thereto. The face part 2 includes a first thin wall region 24 formed by recessing the face rear face 22. The first thin wall region 24 is formed in a toe upper region A1 that is a region on an upper side from a sweet spot SS and on a toe side in a face front view when being viewed from a direction orthogonal to the face 21. The first thin wall region 24 is formed on an outside from a region A2 that is a 5 mm radius about the sweet spot SS. The first thin wall region 24 has an area having a certain ratio to an area of the toe upper region. The first thin wall region 24 is a single region having a closed outline. The outline is provided without hanging out of the toe upper region A1.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a golf club head. [Background technology]

[0002] The following Patent Document 1 proposes an iron-type golf club head that can provide a good shot feeling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-284155 Summary of the Invention [Problem to be solved by the invention]

[0004] Golf club heads such as irons, fairway woods, and hybrids often hit a golf ball placed directly on grass, and therefore tend to frequently hit the ball at a position about 15 mm above the lowest end of the face.

[0005] On the other hand, the position on the face where the repulsion is highest is near the sweet spot, but in the case of the golf club head described above, the sweet spot is usually located approximately 20 to 22 mm above the lowest end of the face. As a result, with this type of golf club head, the main hitting position and the position where the repulsion is highest do not coincide, and as a result, there is room for further improvement in terms of improving the flight distance of the ball.

[0006] The present invention was devised in consideration of the above-mentioned problems, and its main object is to provide a golf club head that can lower the sweet spot without compromising durability and improve the repulsion performance at the main hitting position. [Means for solving the problem]

[0007] The present invention is a golf club head having a face portion, the face portion having a face that is the surface for hitting a ball and a face back that is the opposite surface, the face portion having a first thin-walled region formed by recessing the face back, the first thin-walled region being formed in the toe upper region that is above the sweet spot and on the toe side in a front view of the face seen from a direction perpendicular to the face, the first thin-walled region being formed outside an area with a radius of 5 mm centered on the sweet spot, and the area of ​​the first thin-walled region being 15% to 70% of the area of ​​the toe upper region.

[0008] In another aspect of the present invention, the thickness of the first thin region may be in the range of 0.5 to 2.0 mm.

[0009] In another aspect of the present invention, the first thin-walled region may be formed outside a region having a radius of 10 mm centered on the sweet spot.

[0010] In another aspect of the present invention, the first thin-walled region may have the smallest thickness in the face portion.

[0011] In another aspect of the present invention, the face portion includes a face plate and a face support portion having a support surface that supports the peripheral portion of the face plate from the rear of the head, and in a front view of the face, a portion of the first thin-walled region overlaps the support surface, and the first thin-walled region may be separated from the support surface in the fore-and-aft direction of the head.

[0012] In another aspect of the present invention, grooves extending in the toe-heel direction may be formed on the upper and / or lower sides of the back surface of the face.

[0013] In another aspect of the present invention, the thickness of the portion of the face portion where the groove is provided may be greater than the thickness of the first thin region.

[0014] In another aspect of the present invention, the groove may be spaced apart from the first thin-walled region.

[0015] In another aspect of the present invention, the toe side of the groove may communicate with the first thin-walled region.

[0016] In another aspect of the present invention, the face portion is configured to include a face plate and a face support portion having a support surface that supports the peripheral portion of the face plate from the rear of the head, and in a front view of the face, at least a portion of the groove overlaps the support surface, and the groove may be separated from the support surface in the fore-and-aft direction of the head.

[0017] In another aspect of the present invention, the golf club head may be an iron-type golf club head. [Effects of the Invention]

[0018] By adopting the above-described configuration, the golf club head of the present invention can lower the sweet spot without impairing durability, and improve the repulsion performance at the main hitting position. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a front view of the golf club head of the present embodiment. [Figure 2] FIG. 2 is a rear view of the golf club head of the present embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is an exploded perspective view of the golf club head of the present embodiment. [Figure 5] FIG. 2 is a schematic perspective view of a golf club head for explaining a reference state. [Figure 6] (A) is a front view of a golf club head, and (B) is a cross-sectional view of the golf club head taken along line s1. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 2 is a front view of the face of the first embodiment. [Figure 9] FIG. 4 is a diagram showing stress distribution in a face portion. [Figure 10] 9 is a cross-sectional view taken along line XX in FIG. 8. [Figure 11] FIG. 10 is a front view of a face according to a second embodiment. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 11 is a front view of a face according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will now be described with reference to the drawings. The embodiments disclosed below are not intended to be limiting in any way. Furthermore, the disclosed embodiments can be used alone or in various combinations. Furthermore, throughout this specification, identical or common elements are designated by the same reference numerals, and redundant descriptions are omitted.

[0021] 1 to 4 are a front view, a rear view, a cross-sectional view along line III-III in FIG. 1, and an exploded perspective view of a golf club head (hereinafter sometimes simply referred to as "head") 1 according to this embodiment. The present invention can be suitably applied to a head that is often used to hit golf balls placed directly on grass. In this embodiment, an iron-type golf club head is exemplified as such a head. In other embodiments, the head 1 may be configured as, for example, a fairway wood or a utility club.

[0022] The head 1 includes, for example, a face portion 2, a top 3, a sole 4, a toe 5, a heel 6, and a hosel 7.

[0023] The face portion 2 has a face 21, which is the surface for hitting the ball, and a face back surface 22, which is the opposite surface. A plurality of face lines 8 (see FIG. 5) are formed on the face 21 in order to increase friction with the ball. The face lines 8 are grooves that extend in the toe-heel direction. The face lines 8 are omitted in the drawings other than FIG. 5.

[0024] [Reference condition] 1 to 4, the head 1 is in a reference state. In this specification, the "reference state" of the head 1 refers to a state in which the face line 8 formed on the face 21 of the head 1 is parallel to the horizontal plane HP, and the head 1 is placed on the horizontal plane HP, as conceptually shown in FIG. 5. In the reference state, the center axis CL (axis of the club shaft) of the hosel 7 of the head 1 is disposed within the reference vertical plane VP. The reference vertical plane VP is a plane perpendicular to the horizontal plane HP. In this reference state, the face line 8 is parallel to both the horizontal plane H and the reference vertical plane VP. In FIG. 5, α represents the lie angle, and β represents the loft angle. In this specification and claims, unless otherwise specified, the configuration of each part will be described assuming that the head 1 is in the reference state.

[0025] [Head direction] With reference to FIG. 5, the front side of the head 1 means the side of the face 21 in the reference state. The rear or back side of the head 1 means the side opposite the face 21. The front-to-rear direction of the head is the direction of the x-axis, which is perpendicular to the reference vertical plane VP in FIG. 5. The toe-heel direction of the head 1 is the direction of the horizontal y-axis, which is perpendicular to the front-to-rear direction of the head. The up-down direction of the head 1 is the direction of the z-axis, which is perpendicular to both the x-axis and the y-axis, and the "upper side" and "lower side" of the head 1 correspond to the "upper side" and "lower side" in the reference state, respectively.

[0026] [Head structure] 1 and 3, the face 21 includes a sweet spot SS. As shown in Fig. 3, the sweet spot SS is the intersection of a normal N drawn from the center of gravity CG of the head to the face 21 and the face 21. The sweet spot SS is one of the impact points with excellent resilience.

[0027] In the case of the iron-type head 1 of this embodiment, the face 21 is formed as a flat surface. Therefore, in the case of an iron-type head, the face portion 2 is a portion that has such a flat face 21 on the front surface.

[0028] On the other hand, if the head 1 is a fairway wood or a hybrid, the face 21 may be formed with a curved surface having, for example, a roll and / or a bulge. In this case, the face portion 2 is the portion surrounded by the periphery of the face 21. In this specification, the periphery of the face 21 is defined as follows. First, as shown in FIG. 6(A), each cross section s1, s2, s3... including a normal N connecting the center of gravity CG of the head and the sweet spot SS is identified. Then, as shown in FIG. 6(B), a position Pe is determined on each of the cross sections s1, s2, s3... at which the radius of curvature r of the contour line Lf on the outer surface of the head first reaches 200 mm from the sweet spot SS toward the outside of the face. The connection of these positions Pe is defined as the periphery E of the face 21.

[0029] 3, the top 3 extends from the upper edge of the face 21 to the rear of the head 1 so as to constitute, for example, the upper surface portion of the head 1. The top 3 may be called a crown or an "upper part of the head."

[0030] The sole 4 extends from the lower edge of the face 21 rearward of the head 1 so as to form the lower surface portion of the head 1. The sole 4 is sometimes called the "lower part of the head." In this embodiment, a back wall portion 10 is further provided rearward of the sole 4. The back wall portion 10 extends rearward from the back surface 22 of the face toward the upper part of the head. As a result, in the head 1 of this embodiment, a pocket-shaped cavity i is formed rearward of the face portion 2. The back wall portion 10 helps to form the center of gravity CG of the head lower and deeper.

[0031] The toe 5 is the end portion farthest from the hosel 7 in the toe-heel direction of the head 1, and smoothly connects the top 3 and the sole 4. The heel 6 is the end portion located opposite the toe 5 in the toe-heel direction of the head 1, and the hosel 7 is connected thereto.

[0032] The hosel 7 is configured, for example, in a cylindrical shape, and has a shaft insertion hole 7a for receiving a club shaft (not shown) as shown in Fig. 1. A central axis CL of the hosel 7 is defined by the central axis of the shaft insertion hole 7a.

[0033] As shown in FIG. 4, the head 1 of this embodiment is configured by joining, for example, a face plate 100 and a head main body 200 together.

[0034] In this embodiment, the face plate 100 and the head body 200 are made of different metal materials. For example, the face plate 100 is preferably made of a metal material having high strength, such as titanium, a titanium alloy, stainless steel, or maraging steel. For the head body 200, for example, stainless steel or carbon steel for mechanical structures is preferably used.

[0035] The faceplate 100 of this embodiment has a plate shape and has a front surface 101 , a back surface 102 , and side surfaces 103 .

[0036] In this embodiment, the front surface 101 of the faceplate 100 can form the main part of the face 21 .

[0037] In this embodiment, the rear surface 102 of the faceplate 100 constitutes the main portion of the rear face surface 22 .

[0038] In this embodiment, the side surfaces 103 of the face plate 100 include, for example, a side surface 103a on the top 3 side, a side surface 103b on the sole 4 side, a side surface 103c on the toe 5 side, and a side surface 103d on the heel 6 side.

[0039] In a preferred embodiment, of the side surfaces 103 of the face plate 100, at least one, preferably a plurality, and more preferably all of the side surfaces 103a on the top 3 side, the side surface 103b on the sole 4 side, and the side surface 103c on the toe 5 side are formed so as to be exposed to the outer surface of the head. In this embodiment, as shown in Figures 1 and 3, the side surface 103a on the top 3 side, the side surface 103b on the sole 4 side, and the side surface 103c on the toe 5 side of the face plate 100 are exposed to the outer surface of the head so as to constitute the front portions of the head of the top 3, the sole 4, and the toe 5, respectively. Such a face plate 100 forms a wider area of ​​the face 21 and helps to provide high repulsion performance.

[0040] As shown in FIG. 4, the head body 200 includes, for example, a heel 6, a hosel 7, a back wall portion 10, and a face receiving portion 201.

[0041] The face support portion 201 is formed, for example, in an annular shape so as to define an opening O that penetrates in the front-to-rear direction of the head, and includes a top-side support portion 201a, a sole-side support portion 201b, a toe-side support portion 201c, and a heel-side support portion 201d. The top-side support portion 201a, the sole-side support portion 201b, and the toe-side support portion 201c form the rear of the top 3, the rear of the sole 4, and the rear of the toe 5 of the head 1, respectively. These support portions distribute a large amount of weight to the peripheral edge side of the face portion 2, and serve to increase the moment of inertia of the head 1.

[0042] The face support portion 201 also has a support surface 202 that supports the peripheral edge portion 100e of the face plate 100 from the rear of the head. In this embodiment, the support surface 202 is formed in an annular shape so as to connect the top-side support portion 201a, the sole-side support portion 201b, the toe-side support portion 201c, and the heel-side support portion 201d. The face plate 100 and the head main body 200 are fixed to each other by various joining methods such as welding, brazing, or crimping so that the support surface 202 and the face back surface 22 come into contact with each other.

[0043] As described above, the face portion 2 of the head 1 of this embodiment is configured as a composite of the face plate 100 and the face support portion 201, but the head 1 of the present invention is not limited to this configuration. In another configuration, the head 1 of the present invention may have a one-piece structure integrally formed by casting, forging, or the like.

[0044] Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 1. As shown in Fig. 1 and Fig. 7, a first thin region 24 is formed in the face portion 2 by recessing the face back surface 22. The first thin region 24 in this embodiment is formed by recessing the back surface 102 of the face plate 100.

[0045] The first thin-walled region 24 includes, for example, a portion with a thickness t1. This thickness t1 is relatively small in the face portion 2. In this embodiment, the thickness t1 of the first thin-walled region 24 is formed to be the smallest in the thickness distribution of the face portion 2.

[0046] [First embodiment] 8 is a face front view seen from a direction perpendicular to the face 21. As shown in FIG. 8, the first thin-walled region 24 of the first embodiment is formed in a toe upper region A1, which is an area above the sweet spot SS and on the toe side. In the face front view, the toe upper region A1 is an area above a horizontal line L1 passing through the sweet spot SS and on the toe side of a vertical line L2 passing through the sweet spot SS and perpendicular to the horizontal line L1.

[0047] In this embodiment, the first thin-walled region 24 is a single region having a closed contour, and this contour does not extend beyond the toe upper region A1. In other embodiments, the first thin-walled region 24 may extend beyond the toe upper region A1.

[0048] In addition, in the face front view, the first thin-walled region 24 is formed outside of a region A2 having a radius of 5 mm and centered on the sweet spot SS. In other words, the first thin-walled region 24 does not extend into the region A2. Therefore, the region A2 is formed with a thickness greater than the thickness t1 of the first thin-walled region 24.

[0049] Furthermore, in the face front view, the area of ​​the first thin region 24 is 15% to 70% of the area of ​​the toe upper region A1, where the area of ​​the toe upper region A1 is the area of ​​the region surrounded by the straight lines L1 and L2 and the head outline in the face front view.

[0050] [Operation of this embodiment] In the head 1 of this embodiment, the first thin-walled region 24 is formed in the toe upper region A1, thereby reducing the weight above the sweet spot SS and thereby providing a lower sweet spot SS. Therefore, the head 1 of this embodiment improves resilience when hitting a ball at a relatively low position on the face 21. In other words, the resilience at the main hitting position of the head, such as an iron, fairway wood, or hybrid, is improved, thereby increasing the flight distance of the ball. In a preferred embodiment, the area and / or thickness of the first thin-walled region 24 can be adjusted to position the sweet spot SS within a range of 19 to 21 mm from the horizontal plane HP.

[0051] The inventors also investigated the stress distribution on the face of an iron-type head when hitting a ball. The ball hitting position was 15 mm above the bottom edge of the face and at the center of the face in the toe-heel direction. Figure 9 shows the results, with stress represented by different shades of color. Figure 9 is also a diagram of the face as seen from the backside. As is clear from Figure 9, the greatest stress occurs at the hitting position S1, but only very little stress occurs in the above-mentioned toe region A1, which is barely deflected.

[0052] In the head 1 of this embodiment, the first thin region 24 is formed in the toe upper region A1, making the toe upper region A1 more flexible. Therefore, the head 1 of this embodiment promotes the flexibility of the toe upper region A1, which previously barely flexed, when hitting a ball, thereby expanding the flexible region of the face 21 and further improving resilience. Furthermore, the provision of the first thin region 24 makes the face 21 more flexible even when the ball is hit above the sweet spot SS, thereby improving the resilience performance at the upper impact point and, as a result, expanding the high-resilience area.

[0053] Since there is a possibility that the ball will actually be hit near the sweet spot SS, the first thin-walled region 24 is formed outside of a region A2 having a radius of 5 mm and centered on the sweet spot SS. This allows the above-mentioned effect to be achieved without impairing the durability of the face portion 2. To further reliably prevent a deterioration in the durability of the face portion 2, the first thin-walled region 24 is preferably formed outside of a region A3 having a radius of 10 mm and centered on the sweet spot SS, and more preferably outside of a region A4 having a radius of 15 mm.

[0054] Furthermore, because the area of ​​the first thin-walled region 24 is 15 to 70% of the area of ​​the toe upper region A1, the toe upper region A1 achieves both durability and large deflection when hitting a ball. In other words, if the area of ​​the first thin-walled region 24 is less than 15% of the area of ​​the toe upper region A1, the toe upper region A1 will not be able to sufficiently deflect when hitting a ball, which will tend to make it difficult to achieve a low sweet spot SS or an increased high-rebound area. Conversely, if the area of ​​the first thin-walled region 24 exceeds 70% of the area of ​​the toe upper region A1, the durability of the face portion 2 may be reduced. To achieve these various performance characteristics at a higher level, the area of ​​the first thin-walled region 24 is preferably 20% or more, more preferably 25% or more, of the area of ​​the toe upper region A1, but may also be preferably 60% or less, more preferably 50% or less.

[0055] [Face thickness] In this embodiment, the thickness t1 of the first thin-walled region 24 is not particularly limited, but is set to, for example, 0.5 mm or more, preferably 1.0 mm or more, and more preferably 1.2 mm or more so as not to impair durability. Also, the thickness t1 of the first thin-walled region 24 is set to, for example, 2.0 mm or less, preferably 1.8 mm or less, and more preferably 1.6 mm or less so as to further enhance the effect of lowering the sweet spot SS and making the toe upper region A1 more flexible.

[0056] The reference thickness t2 of the face portion 2 (in this embodiment, it is the maximum thickness t2 of the face plate 100, and the same applies below) is not particularly limited, but in order to more reliably prevent deterioration of durability, it is preferably larger than the thickness t1, and may be, for example, 1.0 mm or more, preferably 1.5 mm or more, and more preferably 1.8 mm or more. Moreover, in order to make the face portion 2 more flexible, the thickness t2 of the face portion 2 may be, for example, 3.0 mm or less, preferably 2.5 mm or less, and more preferably 2.2 mm or less.

[0057] [First thin-walled region] 8, the first thin-walled region 24 may be provided so as to extend widely on the outer periphery of the face 21 in order to more effectively facilitate flexing of the toe upper region A1. For example, in the face front view of FIG. 8, a portion of the first thin-walled region 24 may be formed so as to overlap the support surface 202 of the head body 200.

[0058] 10 is a cross-sectional view taken along line XX in Fig. 8, and as shown in Fig. 10, the first thin-walled region 24 overlapping the support surface 202 is preferably spaced apart from the support surface 202 in the front-to-rear direction of the head. In this embodiment, the first thin-walled region 24, which is prone to flex when hitting a ball, can be extended toward the outer periphery of the face 21 without being restricted by the support surface 202, which is preferable in that the face 21 can be configured to be even more prone to flex.

[0059] [Second embodiment] A front view of the face of the second embodiment is shown in Fig. 11. As shown in Fig. 11, the head 1 of this embodiment further has grooves 26 extending in the toe-heel direction formed on the upper and / or lower sides of the back surface 102 (shown in Fig. 4) of the face plate 100 serving as the face back surface 22.

[0060] In this embodiment, the grooves 26 include a groove 26a on the top side and a groove 26b on the sole side, but only one of them may be provided.

[0061] The top-side groove 26a extends in the toe-heel direction above the sweet spot SS. The sole-side groove 26b extends in the toe-heel direction below the sweet spot SS. Both grooves 26a, 26b extend along the contour of the face 21, crossing the vertical line L2. The toe sides of the top-side groove 26a and the sole-side groove 26b have closed ends and are configured to be separated from the first thin-walled region 24.

[0062] FIG. 12 is a cross-sectional view taken along line XII-XII of FIG. 10. As shown in FIG. 12, the portion of the face portion 2 where the groove 26 is provided is thinned and has a wall thickness t3. This wall thickness t3 is smaller than the reference wall thickness t2 of the face portion 2. Therefore, in the head 1 of this embodiment, when hitting a ball, the upper part and / or the lower part of the face 21 is more likely to bend, so that the high-rebound area is further enlarged.

[0063] In a preferred embodiment, as shown in FIG. 11, the groove 26 may be provided so as to be located more on the outer peripheral side of the face 21 in order to bend the face portion 2 more. For example, in the front view of the face in FIG. 11, a part of the groove 26 (in this embodiment, the sole-side groove 26b) may be formed so as to overlap the support surface 202 of the head body 200.

[0064] On the other hand, as shown in FIG. 12, the groove 26 (the sole-side groove 26b in this example) that overlaps the support surface 202 is preferably separated from the support surface 202 in the front-rear direction of the head. In such an embodiment, the portion of the groove 26 that is easily bent during ball hitting can be positioned on the outer peripheral side of the face 21 without being restricted by the support surface 202, and thus it is preferable in that the face 21 can be configured to be more easily bent.

[0065] The wall thickness t3 of the portion where the groove 26 is provided is not particularly limited, but from the viewpoint of ensuring the durability of the face portion 2, for example, it is preferably in the range of 1.50 to 2.0 mm. In particular, it is desirable that the wall thickness t3 of the groove 26 is larger than the wall thickness t1 of the first thinned region 24. That is, it is preferable that the wall thickness of the face portion 2 is t1 < t3 < t2.

[0066] The width w (shown in FIG. 12) of the groove 26 is, for example, 0.5 mm or more, preferably 1.0 mm or more, more preferably 1.5 mm or more, but from the viewpoint of maintaining the durability of the face portion 2, for example, 3.0 mm or less, preferably 2.5 mm or less, more preferably 2.0 mm or less.

[0067] In the second embodiment, if a groove 26 exists that is separated from the first thin-walled region 24 and a portion of this groove 26 extends within the toe upper region A1, the "area of ​​the first thin-walled region 24" is defined as the total area of ​​the first thin-walled region 24 and the groove 26 within the toe upper region A1.

[0068] [Third embodiment] Fig. 13 shows a front view of the face of the third embodiment. As shown in Fig. 13, the head 1 of the third embodiment also has grooves 26 extending in the toe-heel direction formed on the upper and / or lower side of the back surface 102 (shown in Fig. 4) of the face plate 100 serving as the face back surface 22. However, the third embodiment differs from the second embodiment in that the toe sides of the top-side grooves 26a and the sole-side grooves 26b are connected to the first thin-walled regions 24. This aspect is preferable because the first thin-walled regions 24 and the grooves 26 cooperate to configure the face 21 to be more flexible.

[0069] In the third embodiment, if there is a groove 26 that communicates with the first thin-walled region 24 and a portion of this groove 26 extends within the toe upper region A1, the "area of ​​the first thin-walled region 24" is defined as the total area of ​​the first thin-walled region 24 and the groove 26 within the toe upper region A1.

[0070] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above specific disclosure, and can be implemented in various modified forms within the scope of the technical idea described in the claims. [Example]

[0071] In order to confirm the effects of the present invention, more detailed examples of the present invention will be described, but the present invention should not be construed as being limited to these examples.

[0072] Iron-type golf club heads (embodiments) having the basic structure shown in Figures 1 to 4 were prototyped based on the specifications in Table 1, and their performance was tested (embodiments). For comparison, golf club heads outside the present invention (comparison examples) were also tested in the same manner. Comparison example 1 has a face plate with a constant thickness (thickness t2). The main common specifications are as follows: Club number: I#6 Head weight: 260g Thickness of the first thin-walled area t1: 1.55 mm Standard faceplate thickness t2: 2.10 mm For heads with grooves, the thickness of that part t3: 1.65 mm Groove width: 2mm

[0073] To measure resilience, COR was calculated using computer simulation. COR stands for Coefficient of Restitution and was calculated based on the "Interim Procedure for Measuring the Coefficient of Restitution of an Iron Clubhead Relative to a Baseline Plate Revision 1.3 January 1, 2006" prescribed by the USGA (United States Golf Association). The higher the COR value, the better the resilience of the face at the measurement location. COR values ​​were calculated at two locations: the sweet spot (SS position) and a position 15 mm above the bottom edge of the face and midway in the toe-heel direction (lower impact position).

[0074] In addition, a durability test was conducted. In this test, iron-type golf clubs (total length 38 inches) were prototyped by attaching the same FRP club shaft to each golf club head, and these were attached to a swing robot. The head speed was adjusted to 39 m / s and golf balls were hit with each club, and the number of hits until damage to the face was observed was measured (maximum of 10,000 hits). Measurements were made visually after every 100 hits. The higher the result, the better the durability. If no damage occurred, it was marked as "No damage." The results of the tests are shown in Table 1.

[0075] [Table 1]

[0076] As a result of the test, it was confirmed that the head of the example had a lower sweet spot and improved COR at the lower hitting position without impairing durability. [Explanation of symbols]

[0077] 1 golf club head 2 Face section 5 Tou 6 Heel 21 Face 22 Back of face 24 1st thin area 26 Groove 100 faceplates 100e Faceplate periphery 102 Back of faceplate 200 Head body 201 Face support 202 Support surface A1 Upper toe area SS Sweet Spot

Claims

1. A golf club head having a face portion, the face portion has a face that is a surface for hitting a ball and a face back surface that is the opposite surface thereof, a first thin-walled region is formed in the face portion by recessing the back surface of the face, In a face front view seen from a direction perpendicular to the face, the first thin-walled region is formed in a toe upper region that is a region above the sweet spot and on the toe side, the first thin-walled region is formed outside a region having a radius of 5 mm centered on the sweet spot, The area of ​​the first thin-walled region is 15% to 70% of the area of ​​the toe upper region; the first thin-walled region is a single region having a closed contour, The contour is provided without extending beyond the toe upper region, the face portion includes a face plate and a face receiving portion having a support surface that supports a peripheral portion of the face plate from the rear of the head, In a front view of the face, a portion of the first thin-walled region overlaps the support surface, the first thin-walled region is spaced from the support surface in the head front-rear direction; Golf club head.

2. 2. The golf club head according to claim 1, wherein the thickness of the first thin region is in the range of 0.5 to 2.0 mm.

3. 3. The golf club head according to claim 1, wherein the first thin-walled region is formed outside a region having a radius of 10 mm centered on the sweet spot.

4. 4. The golf club head according to claim 1, wherein the first thin region has the smallest thickness in the face portion.

5. A golf club head having a face portion, the face portion has a face that is a surface for hitting a ball and a face back surface that is the opposite surface thereof, a first thin-walled region is formed in the face portion by recessing the back surface of the face, In a face front view seen from a direction perpendicular to the face, the first thin-walled region is formed in a toe upper region that is a region above the sweet spot and on the toe side, the first thin-walled region is formed outside a region having a radius of 5 mm centered on the sweet spot, The area of ​​the first thin-walled region is 15% to 70% of the area of ​​the toe upper region; the first thin-walled region is a single region having a closed contour, The contour is provided without extending beyond the toe upper region, A groove extending in a toe-heel direction is formed on the upper side and / or lower side of the back surface of the face. Golf club head.

6. A golf club head as described in claim 5, wherein the thickness of the portion of the face where the groove is provided is greater than the thickness of the first thin-walled region.

7. A golf club head as described in claim 5 or 6, wherein the groove is separated from the first thin-walled region.

8. The face portion is configured to include a face plate and a face receiving portion having a support surface that supports a peripheral portion of the face plate from the rear of the head, In a front view of the face, at least a portion of the groove overlaps the support surface; 8. The golf club head according to claim 5, wherein the groove is spaced apart from the support surface in the front-rear direction of the head.

9. A golf club head as described in any one of claims 1 to 8, which is an iron type.

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